The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Cooling fan assemblies may provide airflow to dissipate heat generated by electronic components. Cooling fan assemblies may include a motor that drives fan blades via a rotor. Traditional cooling fan assemblies include a printed circuit board (PCB) mounted inside the motor. Fan control modules and Hall-effect sensors are mounted on the PCB to control the motor.
Referring now to FIG. 1, a cooling fan system 100 includes a PCB 101 mounted in a motor 102. A motor control module 104 is mounted on the PCB 101. A plurality of wires 105 may electrically connect the PCB 101 to a host device (not shown) via terminals 106 on the PCB 101. An example of a host device is a personal computer.
The motor 102 may include a two-phase brushless direct current (DC) motor. The motor 102 may include four stator poles: pole A1 107, pole A2 108, pole B1 110, and pole B2 112. Each of the stator poles may be wound with stator coils 114. Pole A1 107 and pole A2 108 may collectively be called “pole pair A.” Pole B1 110 and pole B2 112 may collectively be called “pole pair B.”
The motor control module 104 may apply a voltage and/or current to the stator coils 114 of pole pair A to generate a magnetic field between pole A1 107 and pole A2 108. Applying the voltage and/or current to the stator coils 114 of pole pair A may be called “driving phase A.” The motor control module 104 may provide the voltage and/or current to the stator coils 114 of pole pair B to generate a magnetic field between pole B1 110 and pole B2 112. Applying the voltage and/or current to the stator coils 114 of pole pair B may be called “driving phase B.”
The motor 102 includes a rotor 116. The rotor 116 may include at least one permanent magnet. The motor control module 104 may drive phase A and/or phase B to actuate the rotor 116 about an axle 118. The axle 118 may mechanically couple the rotor 116 to a fan 120. While the rotor 116 in FIG. 1 rotates between the stator poles 107, 108, 110, 112, the motor 102 may include a rotor that surrounds the stator poles 107, 108, 110, 112.
The motor control module 104 may alternate between driving phase A and driving phase B to actuate the rotor 116. At least one Hall-effect sensor 122 may be mounted on the PCB 101 to provide an indication of rotation of the rotor 116. For example, the Hall-effect sensor 122 may generate a pulse when a magnetic pole of the rotor 116 passes the Hall-effect sensor 122. The motor control module 104 may determine whether the rotor 116 is rotating based on the pulses from the Hall-effect sensor 122.